The Alcantarea  Odorata is one of the giant bromeliads. They say it reaches approx. 4 feet wide, but I've seen larger. The leaves are slender and when young they are a pale green with silver banding. As they mature the leaves become covered with a silvery white powder that makes it come alive compared to the rest of the landscaping. It actually takes on a soft blue-ish tint in the right light.  The inflorescence is tall and branched and has fragrant flowers.  It can be grown outside in tropical areas and will take many light conditions. It isn't common though and is usually used as a specimen. In the north it makes a great potted plant to put near your entrance where you want to make a statement. The plants for sale are 40" across (like the one pictured fourth). The first and third pictures are taken at Fairchild's Tropical Botanic Gardens.